Standard Operating Procedure

for work with

Chemical name/class: / Sodium Azide (customization required – must complete applicable red sections) / CAS #: / 26628-22-8
PI: / All Duke PIs / Date:
Building: / All Duke Buildings / Room #:
Designated Work Area:
  1. Circumstances of Use:

Sodium azide (NaN3) is a colorless crystalline solid and is readily soluble in water. Sodium azide is a common preservative of samples and stock solutions in laboratories and a useful reagent in synthetic work.
No SOP is required if a lab has ONLY pre-made kits where sodium azide is present as a preservative at 1% concentration or less. Labs should follow the instructions provided with these kits, paying close attention to instructions related to drain disposal. (Accumulated sodium azide can react with lead or copper in plumbing to create explosive metal azides). Thorough flushing of plumbing is recommended.
If sodium azide is used as a reactant instead of a preservative, this section must be customized describing the circumstances of use, along with the “Engineering Controls” and “Work Practice Controls” sections.
  1. Potential Hazards:

Sodium azide is considered a Particularly Hazardous Substance (PHS)- - due to its reactivity and acute toxicity.
Consult the Safety Data Sheet and these other resources:
  • Laboratory Chemical Safety Summary: Sodium Azide, Prudent Practices in the Laboratory(The National Academies Press).
  • Facts About Sodium Azide, Centers for Disease Control and Prevention -
Be aware of these specific hazards:
  • Sodium azide is extremely toxic (LD50 oral [rat] 27mg/kg). Ingesting a small amount can be lethal.
  • On contact with water or acid, sodium azide reacts to form a toxic gas (hydrazoic acid) with a pungent odor. However, the odor may not be strong enough to give sufficient warning. Store sodium azide away from acids.
  • OSHA does not have a Permissible Exposure Limit for sodium azide or hydrazoic acid. The American Conference of Governmental Industrial Hygienists recommends a ceiling limit of 0.29 mg/m3 for sodium azide and 0.11 ppm (ceiling) for hydrazoic acid.
  • When heated to its decomposition temperature of ~275°C, sodium azide may undergo violent decomposition. Store and use sodium azide away from heat.
  • Sodium azide reacts with heavy metals and their salts to form heavy metal azides, which are shock-sensitive explosives. Do not store on metal shelves or use metal items to handle sodium azide (i.e., spatulas). Contact with metal shelves, containers, utensils, and drain pipes can result in formation of heavy metal azides and the risk of explosion.
  • Sodium azide reacts violently with nitric acid, bromine, carbon disulfide, dimethylsulfate, and several heavy metals including copper and lead.

  1. Engineering Controls:

If hydrazoic acid or aerosols may be produced, sodium azide (and sodium azide solutions) must be handled in a chemical fume hood, exhausted biological safety cabinet with negative pressure ductwork, or other exhausted enclosure. Aerosols may be produced during any open handling of dry powder, and during open or pressurized manipulations of solutions. It is recommended that labs post this information sheet on Working Safely with Toxic Powders.
  1. Work Practice Controls:

  • If other specific written procedures are required for work with sodium azide, you must list them hereor attach a step-by-step procedure. (If no further procedures are needed beyond those listed in this template, you can delete this bullet.)
  • Use a less dangerous product than sodium azide if possible, or purchase in dilute solution.
  • Set up a designated area for work with sodium azide and suspensions thereof, and label it.
  • If weighing dry powders and the balance cannot be located in a fume hood or BSC, tare a container then add the powdered sodium azide to the container in a hood and seal the container before returning to the balance to weigh the powder. (Do not use a metal scoop to transfer sodium azide powder!)
  • Change gloves regularly (at least every two hours) and wash hands at the time of the glove change.
  • Do not use a HEPA vacuum for cleaning up sodium azide – sodium azide could react with metal inside the vacuum.
  • Keep containers closed as much as possible.
  • Once work with sodium azide is complete, wipe down the work area with a soap and water solution. (For spills of sodium azide, see Section 9)

  1. Personal protective equipment (PPE):

  • Two pairs of standard nitrile laboratory gloves and a fully buttoned lab coat with sleeves extending to the wrists should be worn when handling sodium azide.
  • If splashes may occur, wear goggles and a face shield. Otherwise, wear standard laboratory safety glasses.
  • In cases where the arms or torso may be exposed to liquid suspensions or dry particles, wear Tyvek sleeves and/or gowns (or other air-tight non-woven textile).

  1. Transportation and Storage:

  • Dry powders must be in sealed shatter-resistant containers during transportation. If the container is not shatter-resistant, use a secondary container.
  • Do not store in a metal container.
  • Keep away from heat and open flame.
  • Store in a cool, dry area.
  • Keep sodium azide powder and strong solutions away from benzoyl choride + potassium hydroxide, bromine, carbon disulfide, chromyl chloride, copper, dibromalonitrile, dimethyl sulfate, lead, barium carbonate, acids (especially sulfuric and nitric), metals , metal salts, and water.

  1. Waste Disposal:

Dispose as chemical waste through OESO. See the Duke Lab Safety Manual and your lab-specific chemical hygiene plan for details.
Do not flush sodium azide (solid or concentrated solution) down the drain — the azide can react with lead or copper in the drain lines and explode.
If sodium azide is not the sole active ingredient and is present in a kit in low concentrations, it is permissible to dispose using the sewer system as long as you flush with copious amounts of water.
  1. Exposures/Unintended contact:

For first aid instructions, consult the Safety Data Sheet and the Lab Emergency Response Guide (flip chart) and/or the Duke Lab Safety Manual/Chemical Safety Section ( ).
Notify your supervisor and, within 24 hours, fill out the report of work-related accident, injury, or illness. (Access the report from click “Forms”, then “Report a Work-Related Accident, Injury, or Illness” under “Most Requested Forms”.)
If there is a risk of inhalation exposure (as with a dry powder spill or reaction of sodium azide with water or acid outside of a chemical fume hood), remove all persons from the contaminated area and contact the OESO spill team.
  1. Spill Procedure:

For cleaning up a small spill of sodium azide, do not use metal instruments. Wipe up solutions with chemical absorbent pads. Cover solids with sand, sweep up, and place in a non-metal container. Once spill has been completely absorbed, wipe the area down at least two times using a soap and water solution. Contact OESO Environmental Programs at 919-684-2794 for pick-up.
Spills of dry powders outside of a chemical fume hood or other enclosure should be referred to the OESO spill response team by calling 911 from a campus phone or 919-684-2444 from any phone.
  1. Training of personnel:

All personnel shall read and fully adhere to this SOP for sodium azide. Sign training checklist or CHP annual review page in lab-specific CHP to indicate review.

12/10/2014:Removed hidden hyperlinks. Shortened sections 7, 8, 9, and 10. Removed signature page (signatures now in lab-specific CHP).